Big Ideas: Chemistry Kindergarten: Humans interact with matter every day through familiar materials. Grade 1: Matter is useful because of its properties. Grade 2: Materials can be changed through physical and chemical processes. Grade 3: All matter is made of particles. Grade 4: Matter has mass, takes up space, and can change phase. Grade 5: Solutions are homogeneous mixtures. Grade 6: Everyday materials are often homogeneous solutions and heterogeneous mixtures. Grade 7: Elements consist of one type of atom, and compounds consist of atoms of different elements chemically combined. Grade 8: The kinetic molecular theory and the theory of the atom explain the behaviour of matter. Grade 9: The electron arrangement of atoms impacts their chemical nature.